a medieval instrument for measuring heights and distances
Jacob's staff in American English
nounWord forms: pluralJacob's staves
1. Astronomy
cross-staff
2. Surveying
a pole providing a firm support for a compass or other instrument
Word origin
[1540–50]This word is first recorded in the period 1540–50. Other words that entered Englishat around the same time include: gondola, horizon, machine, monitor, platform